Electron-discharge device



Oct. 30, 1928. r 1,689,338

J. E. HARRIS v ELECTRON DI S CHARGE DEVI CE Filed Nov. 19, 1921 Patented Oct. 30, 1928.

UNITED STATES PATENT OFFICE.

JAMES E. HARRIS, OF NEWARK, NEW JERSEY, ASSIGNOR TO WESTERN ELEOTRIC COM- PANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

ELECTRON-DISCHARGE DEVICE.

Application filed November 19, 1921; Serial No. 516,297.

This invention relates to electric dischar e vice an alloy known by the commercial name of mischmetal, or some one or more of the constituents of this substance. The principal constituents of this alloy are cerium, lanthanum, praseodymium and neodymium together with small amounts of the other rare earth metals.

Further objects of the invention will become apparent from the following specification and accompanying drawing, wherein is disclosed an electron discharge device embodying the invention.

The device comprises a glass bulb 1 having a reentrant stem 2 from which extends the rod 3. Sealed in the end of the stem 2 are the metallic members 4 and 5, from which are supported the frames 6 and 7 formed of wires, one of which projects be yond the top of each frame. A boat or vessel 8 preferably of molybdenum is electrica lly connected and supported by the wires projecting beyond the ends of the frames 6 and 7. A plate 9 is supported directly above the boat 8 by means of the wires 10 fused in the rod 3. This plate'is slightly spaced from the body 8 and is connected by means of the wire 11 to the lead wire 12.

Lead wires 13 and 14 are connected with the members 4 and 5 respectively. In the boat 8 is provided a supply of finely powdered material known by the commercial, name of mischmetal.

In the operation of this device the lead wires 13 and 14 are connected to the opposite sides of a source of direct electrical energy and the lead Wire 12 is connected to the negative one of the leads 13 and 14,through a second source of direct electrical energy in the well-known manner. Electric current passing through the boat and the mischmetal causes the emanation therefrom of electrons and the potential difference between the plate 9 and the mischmetal produces a space current between these two elements. 4

Instead of using powdered mischmetal as the cathode, a filament'may be used of an alloy of platinum and mischmetal in which the mischmetal content is only a very small percentage of the alloy. -A filament containing 1% of mischmetal and 99% of platinum has been satisfactorily used as an electron emitting cathode.

Mischmetal is an alloy formed from the residue in the manufacture of Welsbach mantels. The raw material used in the manufacture of WVelsbach mantels is monazite sand from which thorium and cerium used in the mantels are extracted. Monazite sand contains the following elements scandium samarium yttrium terbium lanthanum n'eoytterbium cerium lutecium dysprosium celtium europium erbium gadolinium a holmium neodymium thulium praseodymium thorium and it is believed that mischmetal contains all of the above enumerated elements with the exception of thorium.

\Vhat is claimed is:

1. In an electron discharge device, a cathode composed of mischmetal.

2. In an electron discharge device, acath 5. In an electron discharge device, a cathode containing neodymium.

In witness whereof, I hereunto subscribe y 1921 JAMES E. HARRIS.

name this 4th day of November A. D., 

